EP0530246A1 - Method for improving the transmission of information in the form of data packets, in accordance with a distributed queuing protocol. - Google Patents

Method for improving the transmission of information in the form of data packets, in accordance with a distributed queuing protocol.

Info

Publication number
EP0530246A1
EP0530246A1 EP91909477A EP91909477A EP0530246A1 EP 0530246 A1 EP0530246 A1 EP 0530246A1 EP 91909477 A EP91909477 A EP 91909477A EP 91909477 A EP91909477 A EP 91909477A EP 0530246 A1 EP0530246 A1 EP 0530246A1
Authority
EP
European Patent Office
Prior art keywords
access unit
request
counter
transmission
bus
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP91909477A
Other languages
German (de)
French (fr)
Other versions
EP0530246B1 (en
Inventor
Nielen Marcus Josephus Joh Van
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koninklijke PTT Nederland NV
Original Assignee
Koninklijke PTT Nederland NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke PTT Nederland NV filed Critical Koninklijke PTT Nederland NV
Publication of EP0530246A1 publication Critical patent/EP0530246A1/en
Application granted granted Critical
Publication of EP0530246B1 publication Critical patent/EP0530246B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/2852—Metropolitan area networks

Definitions

  • the invention relates to a method for transmitting information in the form of data packets in a communications network which comprises two unidirec ⁇ tional transmission channels of opposing transmission of which is linked both to the first and to the second transmission channel, information being moved, under the control of clock signals, respectively from the first to the last access unit linked to the one transmission channel and from the last to the first access unit linked to the other transmission channel and successive time slots being generated which always comprise the same predetermined number of clock signal cycles, in which time slots at least a number of information bits can be written, an access unit which wishes to transmit a data packet placing a request bit in a time slot in " the transmission channel other than the channel in which the data packet has to be transmitted and each access unit recording the number of request bits passed through and the number of request bits still to be transmitted by said access unit.
  • DQDB protocol use is made of two transmission channels, in general data buses, (1 and 2) with mutually opposing communication directions. A series of successive access units is connected to the two buses. The information to be transmitted is transferred to time slots of a fixed size (53 bytes) .
  • Access units which have data to transmit select one of the two buses, for example using as criterion the location of the access unit to which the data must be transmitted.
  • the data packets to be transmitted are dispatched via the time slots passing by, after first completing an access protocol for the relevant time slot.
  • This access protocol proceeds as follows: An access unit which receives a report for transmission in the transmission direction of bus 1 places, as soon as this is possible, a request bit in a predetermined section of a time slot on bus 2. By this means the access units in the transmission direction of bus 2, that is to say opposite to the transmission direction of bus l, are informed that a report is ready for transmission on bus 1 and that these access units must allow an empty time slot to pass by. In this way, as it were, a distributed FIFO buffer is constructed for each bus. For this mechanism a so-called request counter, a so-called countdown counter and a so-called outstanding request counter are provided in each access unit for each bus.
  • the request counter in each access unit which belongs to bus 2 thus contains an indication with regard to the number of still outstanding requests for transmission on bus 1, while mutatis mutandis the same applies for the request counter in each access unit which belongs to bus 1.
  • Each empty time slot, that is to say a possibility for transmitting data, which passes by on bus 1 results in the reading on the request counter of bus 2 being reduced by one.
  • the relevant access unit When the relevant access unit receives data for transmission on bus l, the contents of the request counter of bus 2 are transferred to the countdown counter of bus 1 and the request counter of bus 2 is reset.
  • the countdown counter consequently contains information with regard to the number of outstanding requests before the relevant access unit received a data packet for trans ⁇ mission, while the request counter from that point in time starts to record the information with regard to the number of still outstanding requests after said data packet has been offered for transmission.
  • a request bit In order that the relevant access unit is able to transmit this data packet a request bit must be transmitted on bus 2; this is effected by increasing the counter reading of the out ⁇ standing request counter of bus 2 by one. As soon as the relevant access unit becomes able to transmit a request bit on bus 2, the counter reading of the outstanding request counter is reduced by one.
  • a request bit is transmitted for each data packet to be transmitted.
  • the counter reading of the countdown counter of bus l is reduced by one, and when the counter reading of the countdown counter consequently becomes zero, the data packet may be dispatched in the first subsequent empty time slot.
  • a drawback of the DQDB protocol is that the capacity of the buses for the transmission of data is not put to optimum use, because a request bit always passes through to the end of the bus, so that the situation can arise that free time slots are reserved when this is no longer necessary, because the access unit which trans ⁇ mitted this request bit has already been able to transmit its data.
  • the empty slot counter thus contains information with regard to the number of possibilities for transmission which an access unit has allowed to pass through. If the counter reading of the empty slot counter is not zero, when a request is received on the other bus by means of a request bit in a time slot, it is then possible, because a possibility for transmission, that is to say an empty time slot, has already been allowed to pass through beforehand by the access unit, for said request bit to be erased by resett ⁇ ing the latter. At the same time, the counter reading of the empty slot counter is reduced by one, because one possibility for transmission is going to be used. If the counter reading of the empty slot counter is zero, each incoming request bit is allowed to pass through and the counter reading of the request counter is increased by one.
  • the two counters can therefore never simultaneously have a counter reading with a value greater than zero.
  • the request counter contains informa ⁇ tion with regard to the number of still outstanding requests for empty time slots. If in this situation an empty time slot passes by, said time slot is allowed to pass through and the counter reading of the request counter is reduced by one.
  • a handshake protocol which involves each station which receives and forwards an empty time slot, as a result of which the counter reading of the empty slot counter of said access unit is increased by one, informing the access unit which for ⁇ warded said empty time slot and is the preceding unit in the transmission direction that said empty time slot has been received.
  • a request bit is trans- mitted in a time slot on the other bus, which results in the counter reading of the empty slot counter in the preceding access unit being reduced by one and the "handshake" request bit being erased.
  • An advantage of the D 3 Q protocol over the DQDB protocol is that request bits do not now pass through the entire bus and reserve no further empty time slots as soon as they have passed by "their" empty time slot.
  • Figure 1 shows, by way of example, three access units or stations 7, 8 and 9.
  • the bus 1 is always indi- cated diagrammatically above these stations and the bus
  • time slots being shown, likewise diagrammatically, as rectangles, which time slots are divided into a first section in which, inter alia, the request bit can be placed, and a second section for the data. If one of these sections is hatched in the figure, this means that it contains, respectively, data or a request bit, while the numeral in the hatched section indicates the station for which the data is intended or the station which has originated the request bit.
  • Figures l a, b, c show three successive steps, a time slot having arrived at the next station in each case.
  • station 7 wishes to transmit data.
  • said station places a request bit in a time slot which, seen in the figure, goes via the bus 2 to the left.
  • Figure lb shows that the status of station 9 does not change.
  • Station 8 reads the contents of the time slot and erases these (destination deletion) and lowers the counter reading of the request counter belonging to this station by one because an empty time slot, and thus a possibility fortransmission, is forwarded. Subsequently, as is shown in Figure lc, station 7 can transmit its data in this empty time slot. However, in station 9 a request for an empty time slot is still recorded in the request counter, whereas station 7 has already transmitted the data. In this way, more time slots are thus reserved than are needed and the effective capacity of the bus is reduced.
  • the aim of the invention is to provide a solution to this problem, by which means it becomes possible, via a communications network having the configuration described above, both in a ring structure and in a structure with buses of finite length, to erase the information in time slots which have reached their destination, without this leading to a reduction in the effective capacity of the network, but, on the contrary, the capacity is utilised to the optimum.
  • the invention provides a method of the abovementioned type, with which data in a time slot can be erased in at least one access unit and with which each access unit which is able to erase data is able to reset received request bits, with which, in said access units for the relevant transmission channel, the number of request bits to be reset by said access unit is recorded, and with which a request bit on a transmission channel is reset by the access unit which receives this request bit when the number of request bits to be reset by said access unit on said channel is greater than the number of request bits still to be transmitted by said access unit over said channel.
  • the method according to the invention can best be understood if it is explained with reference to a diagram which gives an overview of the various statuses a - g of an access unit and which then indicates, in the case of a specific occurrence, which action results from this occurrence for each of the said statuses.
  • a diagram of this type is shown in the appended status diagram. In this context it is emphasised that this diagram shows only those statuses, occurrences and actions in respect of which the method differs from the known DQDB or D 3 Q protocol; in respect of all of the statuses and occurrences which are not shown it is the case that the « actions which result therefrom are the same as in the case of the original DQDB or D 3 Q protocol.
  • a full time slot has arrived via bus 1 at a specific station and said time slot has been read, emptied and forwarded empty by said station; 2) A full time slot has arrived on bus 1 at a specific station and said time slot has been read, emptied and refilled by said station;
  • a time slot is emptied and forwarded empty by a specific station (occurrence 1) and still outstanding requests are recorded at said station, which is the case 3 if the counter reading of the request counter is greater than 0 or that of the countdown counter is greater than 0, as shown in status a and d, this station is then entitled to erase a request bit and the counter reading of the relevant request erase counter is increased by one. In addition, the counter reading of the request counter and that of the countdown counter are reduced by one in the same way as in the original protocol. If, however, the time slot is emptied when the counter reading of the two counters is zero (status c) , nothing occurs in the case of the DQDB protocol. In the case of the D 3 Q protocol the counter reading of the empty slot counter is increased by one, but a handshake protocol is not carried out, which signifies that the counter reading of the outstanding request counter is not increased.
  • a station whose counter reading of the request erase counter has a value greater than 0 can erase as many request bits as the value of the request erase counter indicates. If, on the other hand, the station in question itself still has request bits to transmit, which is indicated by the counter reading of the outstanding request counter being greater than 0, request bits can then be erased only under specific conditions. For this purpose, the counter reading of the outstanding request counter and that of the request erase counter are first compared with one another and the highest counter reading is reduced by the lower or possibly identical counter reading. At the same time, if the time slot passing by contains a request bit, the counter reading of the request counter is increased by one. If the counter reading of the request erase counter is the highest (status e) , a request bit which has been received is then reset.
  • the request bit then remains in position or a request bit is placed if it was not yet placed. If the counter reading of the request erase counter is the same as that of the outstanding request counter, nothing occurs with the request bit and said bit is forwarded to the next station.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Small-Scale Networks (AREA)
  • Communication Control (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)
  • Synchronous Machinery (AREA)
  • Control Of Charge By Means Of Generators (AREA)
  • Control Of Eletrric Generators (AREA)
  • Time-Division Multiplex Systems (AREA)

Abstract

PCT No. PCT/EP91/00907 Sec. 371 Date Oct. 15, 1992 Sec. 102(e) Date Oct. 15, 1992 PCT Filed May 14, 1991 PCT Pub. No. WO91/18461 PCT Pub. Date Nov. 28, 1991.A data packet transmission system having a succession of stations each connected to two buses transmitting in opposite directions, both packets and time-slot requests has its capacity improved by means of a request-erase counter at each station for each bus, making possible more efficient use of time slots. Except for the different combinations of status and expectable occurrence, the queuing protocol known as DQDB, optionally is modified by D3Q protocol, is used. For those ten situations where time-slot-request bit resetting (erasing) comes into play, status is defined by the state of certain counters while expectable occurrences are arrivals at a station's access unit of a time-slot that is empty or contains a data packet or a request bit and also the use, if any, made of the arriving time slot by the access unit of the station. The actions produced in those ten instances are in terms of setting or resetting a request bit and advancing, reducing or resetting contents of one or more counters.

Description

Title: Method for improving the transmission of information in the form of data packets, in accordance with a distributed queuing protocol.
The invention relates to a method for transmitting information in the form of data packets in a communications network which comprises two unidirec¬ tional transmission channels of opposing transmission of which is linked both to the first and to the second transmission channel, information being moved, under the control of clock signals, respectively from the first to the last access unit linked to the one transmission channel and from the last to the first access unit linked to the other transmission channel and successive time slots being generated which always comprise the same predetermined number of clock signal cycles, in which time slots at least a number of information bits can be written, an access unit which wishes to transmit a data packet placing a request bit in a time slot in "the transmission channel other than the channel in which the data packet has to be transmitted and each access unit recording the number of request bits passed through and the number of request bits still to be transmitted by said access unit.
A method of this type is described in European Patent Application EP-A-0203165 under the name QPSX protocol, but in the meantime has become better known in specialist circles by the name DQDB protocol, which name will also be used hereinafter.
According to the DQDB protocol, use is made of two transmission channels, in general data buses, (1 and 2) with mutually opposing communication directions. A series of successive access units is connected to the two buses. The information to be transmitted is transferred to time slots of a fixed size (53 bytes) .
Access units which have data to transmit select one of the two buses, for example using as criterion the location of the access unit to which the data must be transmitted. The data packets to be transmitted are dispatched via the time slots passing by, after first completing an access protocol for the relevant time slot.
This access protocol proceeds as follows: An access unit which receives a report for transmission in the transmission direction of bus 1 places, as soon as this is possible, a request bit in a predetermined section of a time slot on bus 2. By this means the access units in the transmission direction of bus 2, that is to say opposite to the transmission direction of bus l, are informed that a report is ready for transmission on bus 1 and that these access units must allow an empty time slot to pass by. In this way, as it were, a distributed FIFO buffer is constructed for each bus. For this mechanism a so-called request counter, a so-called countdown counter and a so-called outstanding request counter are provided in each access unit for each bus.
If an access unit has nothing to transmit, the passage of a request bit on bus 2 results in the counter reading of the request counter belonging to said bus being increased by one. The request counter in each access unit which belongs to bus 2 thus contains an indication with regard to the number of still outstanding requests for transmission on bus 1, while mutatis mutandis the same applies for the request counter in each access unit which belongs to bus 1. Each empty time slot, that is to say a possibility for transmitting data, which passes by on bus 1 results in the reading on the request counter of bus 2 being reduced by one.
When the relevant access unit receives data for transmission on bus l, the contents of the request counter of bus 2 are transferred to the countdown counter of bus 1 and the request counter of bus 2 is reset. The countdown counter consequently contains information with regard to the number of outstanding requests before the relevant access unit received a data packet for trans¬ mission, while the request counter from that point in time starts to record the information with regard to the number of still outstanding requests after said data packet has been offered for transmission. In order that the relevant access unit is able to transmit this data packet a request bit must be transmitted on bus 2; this is effected by increasing the counter reading of the out¬ standing request counter of bus 2 by one. As soon as the relevant access unit becomes able to transmit a request bit on bus 2, the counter reading of the outstanding request counter is reduced by one. In principle, a request bit is transmitted for each data packet to be transmitted. When an empty time slot passes by on bus l, the counter reading of the countdown counter of bus l is reduced by one, and when the counter reading of the countdown counter consequently becomes zero, the data packet may be dispatched in the first subsequent empty time slot. A drawback of the DQDB protocol is that the capacity of the buses for the transmission of data is not put to optimum use, because a request bit always passes through to the end of the bus, so that the situation can arise that free time slots are reserved when this is no longer necessary, because the access unit which trans¬ mitted this request bit has already been able to transmit its data.
It is pointed out that a protocol which is known in specialist circles by the name D3Q protocol and which can be regarded as an improvement of the DQDB protocol has recently been proposed in the as yet unpublished Swiss Patent Application CH-A-00566/89-8. In this protocol use is made of the same reservation mechanism for time slots as in the DQDB protocol. An important difference from the DQDB protocol is, however, that request bits can be removed from a bus if they have become superfluous because the requesting access unit has already become able to transmit a data packet. This erasure of a request bit is effected in the following way: By means of an empty slot counter, each access unit records the number of time slots passing by on a bus for which no request has been submitted. The empty slot counter thus contains information with regard to the number of possibilities for transmission which an access unit has allowed to pass through. If the counter reading of the empty slot counter is not zero, when a request is received on the other bus by means of a request bit in a time slot, it is then possible, because a possibility for transmission, that is to say an empty time slot, has already been allowed to pass through beforehand by the access unit, for said request bit to be erased by resett¬ ing the latter. At the same time, the counter reading of the empty slot counter is reduced by one, because one possibility for transmission is going to be used. If the counter reading of the empty slot counter is zero, each incoming request bit is allowed to pass through and the counter reading of the request counter is increased by one. The two counters can therefore never simultaneously have a counter reading with a value greater than zero. The request counter contains informa¬ tion with regard to the number of still outstanding requests for empty time slots. If in this situation an empty time slot passes by, said time slot is allowed to pass through and the counter reading of the request counter is reduced by one.
In order to prevent a single passing empty time ~ slot resulting in the request bit being reset in several access units, use is made of a handshake protocol which involves each station which receives and forwards an empty time slot, as a result of which the counter reading of the empty slot counter of said access unit is increased by one, informing the access unit which for¬ warded said empty time slot and is the preceding unit in the transmission direction that said empty time slot has been received. For this purpose a request bit is trans- mitted in a time slot on the other bus, which results in the counter reading of the empty slot counter in the preceding access unit being reduced by one and the "handshake" request bit being erased.
An advantage of the D3Q protocol over the DQDB protocol is that request bits do not now pass through the entire bus and reserve no further empty time slots as soon as they have passed by "their" empty time slot.
However, if the D3Q protocol were to be combined with time slot erasure techniques, such as destination deletion, that is to say the emptying of a time slot when this has arrived at the destination, which can be desirable in order, on the one hand, yet further to increase the efficiency of the use of the transmission channels and, on the other hand, to make it possible to use the D3Q protocol in a ring structure, a problem arises which will be illustrated with reference to Figure
1 a,b,c.
Figure 1 shows, by way of example, three access units or stations 7, 8 and 9. The bus 1 is always indi- cated diagrammatically above these stations and the bus
2 below these stations, the time slots being shown, likewise diagrammatically, as rectangles, which time slots are divided into a first section in which, inter alia, the request bit can be placed, and a second section for the data. If one of these sections is hatched in the figure, this means that it contains, respectively, data or a request bit, while the numeral in the hatched section indicates the station for which the data is intended or the station which has originated the request bit. Figures l a, b, c show three successive steps, a time slot having arrived at the next station in each case.
Assume that, as shown in Figure la, station 7 wishes to transmit data. For this purpose said station places a request bit in a time slot which, seen in the figure, goes via the bus 2 to the left. In the stations 8 and 9 this request bit causes the counter reading of the request counter (RC) to be increased by one, which is indicated by RC = 1. It is then assumed that a full time slot arrives via the other bus with a data packet which is intended for station 8.
Figure lb shows that the status of station 9 does not change. Station 8 reads the contents of the time slot and erases these (destination deletion) and lowers the counter reading of the request counter belonging to this station by one because an empty time slot, and thus a possibility fortransmission, is forwarded. Subsequently, as is shown in Figure lc, station 7 can transmit its data in this empty time slot. However, in station 9 a request for an empty time slot is still recorded in the request counter, whereas station 7 has already transmitted the data. In this way, more time slots are thus reserved than are needed and the effective capacity of the bus is reduced.
If the D3Q protocol is to be used in a ring structure in which the ends of each of the buses are linked together, with a mechanism being provided for erasing the data contents from a time slot when it has reached its destination, this would lead to substantial problems because, as described above, request bits which have become superfluous remain recorded in request counters, which in the course of time would lead to a 1 reduction in the effective capacity and ultimately to the complete standstill of communication on the ring.
The aim of the invention is to provide a solution to this problem, by which means it becomes possible, via a communications network having the configuration described above, both in a ring structure and in a structure with buses of finite length, to erase the information in time slots which have reached their destination, without this leading to a reduction in the effective capacity of the network, but, on the contrary, the capacity is utilised to the optimum.
To this end the invention provides a method of the abovementioned type, with which data in a time slot can be erased in at least one access unit and with which each access unit which is able to erase data is able to reset received request bits, with which, in said access units for the relevant transmission channel, the number of request bits to be reset by said access unit is recorded, and with which a request bit on a transmission channel is reset by the access unit which receives this request bit when the number of request bits to be reset by said access unit on said channel is greater than the number of request bits still to be transmitted by said access unit over said channel. The method according to the invention can best be understood if it is explained with reference to a diagram which gives an overview of the various statuses a - g of an access unit and which then indicates, in the case of a specific occurrence, which action results from this occurrence for each of the said statuses. A diagram of this type is shown in the appended status diagram. In this context it is emphasised that this diagram shows only those statuses, occurrences and actions in respect of which the method differs from the known DQDB or D3Q protocol; in respect of all of the statuses and occurrences which are not shown it is the case that the « actions which result therefrom are the same as in the case of the original DQDB or D3Q protocol.
In the status diagram it is assumed that the data are transmitted via bus 1 and that, therefore, the request bits are transmitted via bus 2. However, the method proceeds in the same way for transmission of data via bus 2 and of request bits via bus 1. Furthermore, in the status diagram a distinction is made between four different occurrences 1-4, which can arise when a time slot passes by an access unit and which, respectively, have the following significance:
1) A full time slot has arrived via bus 1 at a specific station and said time slot has been read, emptied and forwarded empty by said station; 2) A full time slot has arrived on bus 1 at a specific station and said time slot has been read, emptied and refilled by said station;
3) A time slot containing a request bit has arrived on bus 2 at a specific station; and 4) A time slot without a request bit has arrived on bus 2 at a specific station.
Furthermore, for reasons of clarity the following abbreviations have been used in the diagram for the various counters, the bus on which the counter reading can be influenced by occurrences being indicated in brackets after the abbreviation:
RC Request counter CD Countdown counter
RQ.ERASE Request erase counter OUTST.RQ.COUNT Outstanding request counter
ESC Empty slot counter Finally, the following abbreviation is also used: X : Status unimportant
If a time slot is emptied and forwarded empty by a specific station (occurrence 1) and still outstanding requests are recorded at said station, which is the case 3 if the counter reading of the request counter is greater than 0 or that of the countdown counter is greater than 0, as shown in status a and d, this station is then entitled to erase a request bit and the counter reading of the relevant request erase counter is increased by one. In addition, the counter reading of the request counter and that of the countdown counter are reduced by one in the same way as in the original protocol. If, however, the time slot is emptied when the counter reading of the two counters is zero (status c) , nothing occurs in the case of the DQDB protocol. In the case of the D3Q protocol the counter reading of the empty slot counter is increased by one, but a handshake protocol is not carried out, which signifies that the counter reading of the outstanding request counter is not increased.
If, in the event of an occurrence 2, a specific station empties a time slot and fills this again itself, which signifies that there was a data packet to be transmitted and the counter reading of the countdown counter was zero (status b) , the counter reading of the request erase counter is then also increased by one.
A station whose counter reading of the request erase counter has a value greater than 0 can erase as many request bits as the value of the request erase counter indicates. If, on the other hand, the station in question itself still has request bits to transmit, which is indicated by the counter reading of the outstanding request counter being greater than 0, request bits can then be erased only under specific conditions. For this purpose, the counter reading of the outstanding request counter and that of the request erase counter are first compared with one another and the highest counter reading is reduced by the lower or possibly identical counter reading. At the same time, if the time slot passing by contains a request bit, the counter reading of the request counter is increased by one. If the counter reading of the request erase counter is the highest (status e) , a request bit which has been received is then reset. If the counter reading of the outstanding request counter is the highest (status g) the request bit then remains in position or a request bit is placed if it was not yet placed. If the counter reading of the request erase counter is the same as that of the outstanding request counter, nothing occurs with the request bit and said bit is forwarded to the next station.
By means of the invention, with which time slot erasure techniques are combined with queuing protocols such as the DQDB and the D Q protocol, a protocol is obtained with which the capacity of the transmission system is utilised in a more efficient manner because requests are prevented from remaining in access unit counters unnecessarily. Moreover, by means of the measures according to the invention, the principle of both protocols can also be used in a ring structure, which without said measures would irrevocably lead to considerable problems.

Claims

14CLAIMS
1. Method for transmitting information in the form of data packets in a communications network which com¬ prises two unidirectional transmission channels of opposing transmission directions and a series of succes¬ sive access units, each of which is linked both to the first and to the second transmission channel, information being moved, under the control of clock signals, respec¬ tively from the first to the last access unit linked to the one transmission channel and from the last to the first access unit linked to the other transmission channel and successive time slots being generated which always comprise the same predetermined number of clock signal periods, in which time slots at least a number of information bits can be written, an access unit which wishes to transmit a data packet placing a request bit in a time slot in the transmission channel other than the channel in which the data packet has to be transmitted and each access unit recording the number of request bits passed and the number of request bits still to be trans¬ mitted by said access unit, characterised in that data in a time slot can be erased in at least one access unit and in that each access unit which is able to erase data is able to reset received request bits, in that, in said access units for the relevant transmission channel, the number of request bits to be reset by said access unit is recorded, and in that a request bit on a transmission channel is reset by the access unit which receives said request bit if the number of request bits to be reset by said access unit on said channel is greater than the number of request bits still to be transmitted by said access unit over said channel.
2. Method according to Claim 1, characterised in that each of the transmission channels is operated in a ring structure.
3. Method according to Claim 1 or 2, characterised in that the nvunber of empty time slots which have passed by is recorded in each access unit for each of the transmission channels.
EP91909477A 1990-05-21 1991-05-14 Method for improving the transmission of information in the form of data packets, in accordance with a distributed queuing protocol Expired - Lifetime EP0530246B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
NL9001173A NL9001173A (en) 1990-05-21 1990-05-21 METHOD OF IMPROVING THE TRANSFER OF INFORMATION IN THE FORM OF DATA PACKAGES ACCORDING TO A DISTRIBUTED QUEUE PROTOCOL.
NL9001173 1990-05-21
PCT/EP1991/000907 WO1991018461A1 (en) 1990-05-21 1991-05-14 Method for improving the transmission of information in the form of data packets, in accordance with a distributed queuing protocol

Publications (2)

Publication Number Publication Date
EP0530246A1 true EP0530246A1 (en) 1993-03-10
EP0530246B1 EP0530246B1 (en) 1994-08-17

Family

ID=19857123

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91909477A Expired - Lifetime EP0530246B1 (en) 1990-05-21 1991-05-14 Method for improving the transmission of information in the form of data packets, in accordance with a distributed queuing protocol

Country Status (11)

Country Link
US (1) US5416775A (en)
EP (1) EP0530246B1 (en)
JP (1) JPH0716202B2 (en)
AT (1) ATE110206T1 (en)
AU (1) AU648799B2 (en)
CA (1) CA2081658C (en)
DE (1) DE69103526T2 (en)
DK (1) DK0530246T3 (en)
ES (1) ES2061249T3 (en)
NL (1) NL9001173A (en)
WO (1) WO1991018461A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5678007A (en) * 1994-11-22 1997-10-14 Microsoft Corporation Method and apparatus for supporting multiple outstanding network requests on a single connection
US10803039B2 (en) 2017-05-26 2020-10-13 Oracle International Corporation Method for efficient primary key based queries using atomic RDMA reads on cache friendly in-memory hash index

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ATE82097T1 (en) * 1984-12-03 1992-11-15 Univ Western Australia LOG FOR QUEUE.
AU623953B2 (en) * 1988-12-07 1992-05-28 Telstra Corporation Limited A communications method for a shared-medium communications network
EP0381868B1 (en) * 1989-01-17 1994-09-07 Koninklijke Philips Electronics N.V. Method and system for transmitting buffered data packets on a communications network
EP0388574B1 (en) * 1989-03-23 1994-06-15 International Business Machines Corporation Method and apparatus for distributed queue multiple access in a communication system
EP0413066B1 (en) * 1989-08-16 1994-06-15 Hewlett-Packard Company Communications system
AU641688B2 (en) * 1989-09-13 1993-09-30 Telstra Corporation Limited An erase station and a method of erasing slots
US5001707A (en) * 1989-11-02 1991-03-19 Northern Telecom Limited Method of providing reserved bandwidth in a dual bus system
US4977557A (en) * 1989-12-14 1990-12-11 Northern Telecom Limited Method of providing effective priority access in a dual bus system
US5124981A (en) * 1990-03-09 1992-06-23 International Business Machines Corporation Access control method for dqdb network
US5115430A (en) * 1990-09-24 1992-05-19 At&T Bell Laboratories Fair access of multi-priority traffic to distributed-queue dual-bus networks

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9118461A1 *

Also Published As

Publication number Publication date
ATE110206T1 (en) 1994-09-15
EP0530246B1 (en) 1994-08-17
JPH0716202B2 (en) 1995-02-22
NL9001173A (en) 1991-12-16
CA2081658A1 (en) 1991-11-22
DE69103526D1 (en) 1994-09-22
ES2061249T3 (en) 1994-12-01
WO1991018461A1 (en) 1991-11-28
AU648799B2 (en) 1994-05-05
JPH05502359A (en) 1993-04-22
AU7874091A (en) 1991-12-10
US5416775A (en) 1995-05-16
DK0530246T3 (en) 1995-01-02
DE69103526T2 (en) 1995-02-23
CA2081658C (en) 1998-05-05

Similar Documents

Publication Publication Date Title
US5081622A (en) Method and apparatus for distributed queue multiple access in a communication system
US5210750A (en) Method and apparatus for distributed queue multiple access in a communication system
US4429405A (en) Method of transmitting information between stations attached to a unidirectional transmission ring
EP0241113B1 (en) Traffic scheduler for multiple access communication channels
EP0433520B1 (en) Elastic configurable buffer for buffering asynchronous data
EP0228629A2 (en) Time-division multiplexing communication system
EP0083632A4 (en) Idle time slot seizure and transmission facilities for loop communication system.
US5185863A (en) Byte-wide elasticity buffer
US5173898A (en) Multiple-access control for a communication system with order pad passing
EP0436069A2 (en) Method and device for switching fixed-length packets such as ATM cells
TW200414720A (en) Network switching device and network switching method
JP3034683B2 (en) How to monitor transmission bit rate
WO1993015571A1 (en) Smoothing delay-sensitive traffic offered to atm networks
US3904829A (en) Demand driven multiplexing system
CA1263168A (en) Telecommunication system for alternatingly transmitting circuit-switched and packet-switched information
AU648799B2 (en) Method for improving the transmission of information in the form of data packets, in accordance with a distributed queuing protocol
US5935214A (en) Method for transmitting source data and control data in a communication system with a ring structure
EP0393293B1 (en) Method and apparatus for cyclic reservation multiple access in a communications system
WO1997043839A1 (en) Method and apparatus for recovery of peak cell rate tokens in an atm network interface
JP2560910B2 (en) Buffer overflow avoidance method
AU601278B2 (en) Improvements relating to packet switching
JPS58216B2 (en) Kanjiyoutsuushinmoupackettsutsuushinboshiki
JPS60201489A (en) Electronic type time recorder system
JPH0758752A (en) Atm signal transmission equipment
JPS62159553A (en) Communication control equipment

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19920826

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU NL SE

17Q First examination report despatched

Effective date: 19940120

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU NL SE

REF Corresponds to:

Ref document number: 110206

Country of ref document: AT

Date of ref document: 19940915

Kind code of ref document: T

REF Corresponds to:

Ref document number: 69103526

Country of ref document: DE

Date of ref document: 19940922

ITF It: translation for a ep patent filed
REG Reference to a national code

Ref country code: ES

Ref legal event code: FG2A

Ref document number: 2061249

Country of ref document: ES

Kind code of ref document: T3

ET Fr: translation filed
REG Reference to a national code

Ref country code: DK

Ref legal event code: T3

EAL Se: european patent in force in sweden

Ref document number: 91909477.1

REG Reference to a national code

Ref country code: GR

Ref legal event code: FG4A

Free format text: 3013996

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
REG Reference to a national code

Ref country code: CH

Ref legal event code: PFA

Free format text: KONINKLIJKE PTT NEDERLAND N.V. TRANSFER- KONINKLIJKE KPN N.V.

REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GR

Payment date: 20030422

Year of fee payment: 13

Ref country code: CH

Payment date: 20030422

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20030428

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: LU

Payment date: 20030502

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 20030505

Year of fee payment: 13

Ref country code: DK

Payment date: 20030505

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 20030506

Year of fee payment: 13

Ref country code: AT

Payment date: 20030506

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20030512

Year of fee payment: 13

Ref country code: BE

Payment date: 20030512

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20030514

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: ES

Payment date: 20030516

Year of fee payment: 13

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040514

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040514

Ref country code: AT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040514

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040515

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040517

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040531

Ref country code: BE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040531

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040531

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DK

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040601

BERE Be: lapsed

Owner name: KONINKLIJKE *PTT NEDERLAND N.V.

Effective date: 20040531

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20041201

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20041201

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20041203

EUG Se: european patent has lapsed
REG Reference to a national code

Ref country code: DK

Ref legal event code: EBP

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20040514

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20050131

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee

Effective date: 20041201

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.

Effective date: 20050514

REG Reference to a national code

Ref country code: ES

Ref legal event code: FD2A

Effective date: 20040517